1. Field of the Invention
The present invention relates to a device for protecting an occupant in a motor vehicle during a collision, more particularly, the invention relates to a tongue of an inflatable belt device and to the inflatable belt device itself.
2. Description of the Related Art
An inflatable belt device of this type is disclosed, for example, in Japanese Unexamined Patent Publication HO5-85301. As shown in FIGS. 11(a) and 11(b), the inflatable belt device 1 includes a shoulder belt 2 extending diagonally from the right side to the left side of an occupant, a lap belt 3 extending from the right side to the left side of the occupant, a buckle 4 fixed to, for example, a vehicle floor, a tongue 5 to be inserted into and engaged with the buckle 4 when the occupant wears the seat belt, and an intermediate guide 6 for guiding the shoulder belt 2.
The shoulder belt 2 includes a webbing 2a, which is the same as a typical conventional seat belt, and an inflatable belt 2b connected to an end of the webbing 2a. The webbing 2a. is slidably hung in the intermediate guide 6. The other end of the webbing 2a is connected to a seat belt retractor 7 , which has an emergency locking mechanism (ELR) and is fixed to the vehicle body. The webbing 2a is arranged so that it may be wound into the seat belt retractor 7.
The inflatable belt 2b is positioned so that it contacts the occupant, and is connected to the tongue 5 at an end opposite to the end connected to the webbing 2a. The lap belt 3 includes a webbing, which is the same as a typical conventional seat belt, having one end connected to the tongue 5 and the other end connected to a seat belt retractor 8 (ELR), which is fixed to the vehicle body.
A gas generator 9, which is actuated to generate high pressure gas in emergency situations, e.g., a collision, is connected to the buckle 4. The tongue 5 and the buckle 4 have passages allowing gas from the gas generator 9 to flow into the inflatable belt 2b.
The inflatable belt 2b of the shoulder belt 2 has a belt body 2c, which is formed in an envelope shape, and a cover 2d. As shown by the solid lines in FIG. 11(b), the belt body 2c is folded and covered by the cover 2d. Both ends of the cover 2d are then connected, by stitching 2e, so that the inflatable belt 2b maintains a band-like shape during normal operation. The stitching 2e of the cover 2d is easily torn by expansion force of the shoulder belt 2 when the gas generator 9 is actuated so that the inflatable belt 2b is deployed as shown by a two-dot chain line in FIG. 11(b).
The inflatable belt 2b, however, has a tent-like portion in the vicinity of the connection between the inflatable belt 2b and the tongue 5. Similar to what is shown in FIG. 7, the tent-like portion spreads, that is, it gradually thickens in the proximity of the tongue. This tent-like portion has a flabby structure of which the inside is vacant and has a poor feeling when touched.